1. Field of the Invention
The present invention relates to the protection of Radio Frequency (RF) receiving and/or transmitting equipment from undesired RF signals which are of sufficient energy-levels to upset and/or damage them. The invention limits the undesired signal levels to sufficiently low levels to prevent damage and/or upset of the system being protected. The invention does not reflect a significant amount of the undesired signal and so is applicable to low-observable systems. The term limiter includes receiver protection device and terminal protective device.
2. Description of the Prior Art
There is a well established need to protect front-door microwave components from intense RF energy. Front-door microwave components are those components located along intentional RF receiving and transmitting paths connected to an antenna in an RF system. Conventional limiter technology takes advantage of a conditional short to ground which serves to reflect the unwanted energy back towards the source. This situation is undesirable for low-observable platforms, because the energy reflected from the limiter makes the platform observable when illuminated by an intense signal (such as an intense radar signal or high power microwave signal).
This is also an undesirable situation for diagnostic equipment such as oscilloscopes, spectrum analyzers, etc. There is a need for this equipment to be protected from incidental transients, however thse transients must not be reflected towards the source. Present limiter technology does not have the ability to solve both of these problems.
Accordingly, it is an object of this invention to provide a limiter that distributes power to the linear and non-linear resistive elements within it, thus providing a limiter with a high burnout threshold.
It is also another object of this invention to provide a limiter with low insertion loss, that is small in size, and that requires little or no power from the system.